This is shaping up to be the year of the look-how-badly-the-West-treats-Africa movie. First there was “Hotel Rwanda” (technically an under-the-wire 2004 release), a wrenching and altogether too accurate portrait of Western indifference to African suffering. More recently, we got “The Constant Gardener,” a preposterous but nonetheless earnestly crafted broadside against the pharmaceutical industry. Now comes “Lord of War,” a Nicholas Cage vehicle about the international arms trade that never quite makes up its mind whether it wants to be a political polemic or a black comedy. This rapid devolution is further evidence that, in Hollywood as in Africa, things fall apart.

Written and directed by Andrew Niccol (“Gattica,” “S1m0ne”), “Lord of War” opens with a bravura sequence tracing the lifespan of a bullet, from birth (its own) to death (its victim’s). We view its conveyor-belt manufacture in an ammunition factory and its subsequent shipment to a buyer. We watch it loaded into a rifle, where it waits with its fellow rounds for the trigger to be pulled. And, finally, we see it launched through the air and into the skull of an African boy perhaps 12 years old. For better and worse, this sequence captures the movie in microcosm: a series of stylish provocations that culminates in a bout of ostentatious moralizing.

Mr. Cage plays Yuri Orlov, a young Ukrainian-American whose family immigrated to Brighton Beach by pretending to be Jewish. His parents and younger brother Vitaly (Jared Leto) run a Crimean restaurant, but Yuri longs for something more. When he witnesses an attempted hit by the local Russian mob, he has an epiphany: As long as people want to kill one another, someone will have to supply them with the means to do so. Using his synagogue connections, Yuri gets his hands on some Israeli-made Uzis, and an arms dealer is born.

For most of its length, “Lord of War” follows the drug-dealer biopic model (“Scarface,” “Blow,” etc.) with AK-47s substituted for cocaine. Yuri’s business grows exponentially and he becomes rich, eventually acquiring a trophy wife (Bridget Moynahan), and enemies both licit (Ethan Hawke as a federal agent) and illicit (Ian Holm as a rival arms dealer). During Yuri’s rise, “Lord of War” plays as a picaresque comedy. We’re meant to admire his charm and resourcefulness, his sexual conquests and narrow escapes, the elaborate cons he engineers on his future wife as well as on his antagonists in law enforcement. Mr. Cage helps us along with near-incessant narration that alternates between comic asides (“I supplied every army but the Salvation Army”) and brief lessons on such professional arcana as the value of the arms smuggled out of the Ukraine after the Cold War ($32 billion) and the provenance of conflict diamonds (“a common currency in West Africa”).

It’s a clever conceit for a movie, but Mr. Niccol never quite manages to bring it off. Mr. Cage’s voiceover is listless, and does little to rescue the occasionally hamfisted writing. (“Despite the other women, I always made love to Eva as if she was the only one.”) In a film that required a delicate touch, Mr. Niccol’s musical choices are crushingly obvious: A montage encapsulating Yuri’s early success is scored to “Money (That’s What I Want)”; a cocaine binge by Yuri and brother Vitaly to, yes, “Cocaine.”

Yuri earns our sympathy in large part because none of the other characters in the film seem to deserve it. The eye-candy wife is a failed actress, failed painter, and “not much good as a mother. “Younger brother Vitaly is an embarrassing screw-up with a penchant for drugs and hookers. Jack Valentine, the federal agent pursuing Yuri, suffers from a strained, one-note performance by Mr. Hawke. And Mr. Holm is barely on screen enough to register at all.

The one pleasant surprise among the cast is Eamonn Walker (“Tears of the Sun,” “Oz”), as a Liberian dictator named Andre Baptiste (closely based on real-life war criminal Charles Taylor). In the latter half of the movie, Yuri begins selling arms to Baptiste, a murderous thug who chops off the hands of his opponents and commands an army of drug-addled boys. After Yuri briefly tries to go legit, he’s persuaded by Baptiste to make one final sale, and asks his brother to go with him to Africa to complete the deal. Vitaly at first says no – he’s cleaned up his act and is now dating a good woman he believes may be “the one” – but ultimately succumbs to Yuri’s entreaties. Anyone who cannot guess how this turns out has, in all likelihood, never seen a movie before. Suffice it to say that Yuri is revealed, once and for all, as a moral monster.

Or is he? Mr. Niccol shifts the film’s ethical frame once more when, after his arrest, Yuri explains to Valentine that he is only small potatoes: The real arms dealers are the governments of United States, England, France, Russia, and China. (In an onscreen postscript Mr. Niccol helpfully points out that these are also the permanent members of the U.N. Security Council.) It’s a true enough point, but one that rather pulls the rug out from under the entire movie. Having been encouraged to treat Yuri first as the film’s hero and subsequently as its villain, we’re finally told that in fact he’s neither – all along, the important action was taking place off-screen, at the White House or on Downing Street. By its own admission “Lord of War” is just a sideshow – and not a particularly memorable one at that.